Question

I’m writing an app for Android (2.1+), and I’d like to use the telephone number of the current phone. Lots of googling brought me the following:

String number=(TelephonyManager)getApplicationContext().getSystemService(Context.TELEPHONY_SERVICE).getLine1Number();

That along with permission: READ_PHONE_STATE.

My problem however is that it returns null. While searching, I noticed this question has been asked many times before and nearly in all of those questions it is said that the number simply isn’t always available.

While testing I found that on my very own phone it gives me null. BUT another app (for example, WhatsApp) was able to recognize my phone number).

So then I wonder, how did they do it?

Answer 1

Well, I came up with another method to retrieve the telephone number (which in my case really is a absolute must-have).

1. The app must connect to a server.
2. The server gives the app a unique id and a telephone number.
3. The app sends a text message to the telephone number with the unique id.
4. The server (did I mention an SMS gateway should allow you to interpret the text message?) will see the number which sent the text message and the id that belongs to the app. This is stored in the database.
5. Now you’ll have the means to retrieve the number using the identifier.

That’s the basic idea.